[4] In 2010, the regulator advised Royal Mail to cease supply of county data altogether,[5] and a timetable was put in place for this to occur between 2013 and 2016.

He went to explain that: Postal addresses are in effect routing instructions for Post Office sorters and, in settling what they should be, the main concern is to ensure a quick and efficient service at reasonable cost.

Second, the London postal district, which formed a special post town, did not conform to any administrative boundaries.

In contrast, Middlesex remained part of the postal address for Staines, Sunbury and Ashford, which had transferred to Surrey.

[15] Furthermore, retaining the existing postal county boundaries was explained as largely due to cost reasons.

The Times pointed out that this might cause confusion, noting that in future "children will no doubt wonder why their address should refer to a county in which they have never lived", but that "some people […] want the name of Middlesex preserved because of its historical associations".

[16] The Local Government Act 1972 redrew the administrative county map of England and Wales outside Greater London.

[18] When the local government changes came into force, the Post Office announced that the new counties would form part of postal addresses from 1 July 1974, and should be used as "soon as possible".

"[19] The postal counties listed in 1961 that did not continue after the reforms were Cumberland, Rutland, Sussex, Westmorland and Yorkshire.

Gordon Oakes, Parliamentary Under Secretary of State at the Department of the Environment, explained the policy in a written answer to a question in parliament, shortly after the changes were brought in:[21] Postal addresses are routing instructions, not geographical descriptions, and the extent to which the new county names are being adopted for mail has been the subject of advice issued by the Post Office.The postal county was omitted for addresses within 110 post towns.

Following the Local Government Act 1972, addresses in these post towns required the new postal county.

According to Royal Mail policy the field is not updated and where new post towns are created they will not be assigned to a former postal county.

This continued use has caused customers in areas where there is discrepancy between the postal and geographic counties to complain to Royal Mail.

Until 2007 the Royal Mail position was that under their current code of practice, changes to county data will not be considered.

[3][25] However, after a lengthy and well-organised campaign,[26] the Royal Mail agreed to create a postal county of Rutland in 2007.

[27] In contrast, Seaton Delaval residents had unsuccessfully campaigned in 2004 to be removed from the former postal county of Tyne and Wear.

[12] In 2009 the Royal Mail code of practice came up for renewal, and the regulator Postcomm held a public consultation on its future.

In May 2010 Postcomm decided to advise Royal Mail to "discontinue provision of such information at the earliest opportunity".